The present invention relates generally to electromagnetic projectile launching systems, and more particularly to electromagnetic rail guns.
Electromagnetic projectile launchers include rail gun systems. Such systems normally use a pair of conductive rails, a sliding conductive armature between the rails, a source of high current, and a means of commutating this current into the rails and through the armature. This places an electromagnetic force on the armature and propels it along the conductive rails. By placing a projectile in front of the armature and activating the rail gun, the projectile is propelled by the movement of the armature.
Exemplary in the art of electromagnetic projectile launching systems are the systems described in the following U.S. Patents, the disclosures of which are incorporated herein by reference:
U.S. Pat. No. 1,370,200 issued to Fauchon-Villeplee; PA1 U.S. Pat. No. 1,422,427 issued to Fauchon-Villeplee; PA1 U.S. Pat. No. 4,433,608 issued to Deis et al; and PA1 U.S. Pat. No. 4,480,523 issued to Young et al.
The early Fauchon-Villeplee patent No. 1,3700,200 disclosed an electric gun for propelling projectiles having conductive wings. A cross-shaped projectile is shown in the later Fauchon-Villeplee patent No. 1,422,427. In this early design, the projectile and armative were one and the same. However, the more modern approach used a separate armature to launch projectable so that they are not constrained to have conductive wings. This modern approach is more suitable to the present need, since the modern projectiles may have complex electronic circuitry and they are more than inert payloads or explosives, as envisioned in the past.
Deis et al and Young et al are excellent examples of modern rail gun systems. Deis et al show a rail gun with elements having a rectangular cross-section. Young et al show a multiple rail, multiple armature construction in which armatures carried by a cylindrical core are located between the rails.
The systems of Deis et al and Young et al free the projectiles from the constraints of the Fauchon-Villeplee references. However, a recently developed concern entails the task of magnetically shielding modern projectiles from the magnetic field used in rail guns. As hinted earlier, modern projectiles may be more than inert payloads. These projectiles may have complex electronic circuitry of their own for a number of tasks that they perform. While magnetically shielding modern projectiles is a solution to this concern, shielding alone is an inadequate approach, for the reason discussed below.
Magnetic shielding of electronic components from magnetic fields commonly entails imposing a shield (often of a ferrous material) between the components and the magnetic field. The stronger the field, the more shielding may be required to reduce the magnetic field to a threshold that doesn't interfere with the electronic component. The task of shielding projectiles from the magnetic fields used in rail guns is made easier if the magnetic field is reduced. Also, the weight of the shielding may be reduced if the magnetic field is reduced.
From the foregoing discussion, it is apparent that there currently exists the need to reduce the level of magnetic fields of electromagnetic rail guns. The present invention is intended to satisfy the need.